The present invention pertains to a door latch system, particularly for the side doors of motor vehicles, more particularly for those of passenger cars.
Passenger car side door latch systems in general comprise a latch assembly on a door and a striker on the opposing member of the vehicle body. As heretofore constructed, the latch assembly typically comprises: (1) a latch member (or rotor) engageable with the striker upon closure of the door; (2) a ratchet for restraining the latch member from rotation in a direction to release the striker; (3) a release lever for causing the ratchet to disengage the latch member; and (4) a locking lever for preventing the release lever from acting on the ratchet and hence for locking the door against accidental or undesired opening. All of these components of the latch assembly move in parallel planes, and some of them in coplanar relation to each other, in accordance with the prior art.
One of the objections to this known type of latch system concerns the linkages for operating the latch assembly from within the vehicle. The release lever is actuated from both outside.and inside handles on the vehicle door, whereas the locking lever is actuated from a knob on the window sill of the door. The linkage between the inside handle and the release lever, and the linkage between the knob and the locking lever, both move in planes normal to the planes of the listed components of the latch assembly. Inevitably, therefore, undesirable three-dimensional power transfers are required from the final elements of the linkages to the release and locking levers, as will be later explained in more detail with reference to the drawings attached hereto.
Another objection to the prior art is the arrangement of the latch components. In the prior art system the main body or frame of the latch assembly essentially houses only the latch member and the ratchet. The release lever, the locking lever, and the other associated means are mounted externally on the body, in parallel relation to the latch member and the ratchet. In addition to these, the body must externally support the noted final elements of the linkages in an upstanding attitude. Thus the configuration of the parts on the outside of the body is complex and unorderly and makes difficult the manufacture and assemblage of the device.
A further problem manifests itself in conjunction with the latch systems on the rear doors of four-door passenger cars. While the latch systems on the front and rear doors are essentially identical, the designs of four-door passenger cars often require the latch assemblies on the rear doors to be oriented out of the perpendicular. This orientation of the latch assemblies has heretofore incurred considerable losses in power transmission from the outside handles.
An additional problem resides in the mechanism for making the latch system "childproof", that is, unopenable by children tampering with the inside handle. Since the conventional latch assembly itself is very complex in construction as discussed hereinbefore, the addition of the childproofing mechanism has rendered it still more so.